Train of Four
Train of Four is the test used to measure the degree of neuromuscular blockade. A peripheral nerve stimulator is used.
- Do a baseline measurement before paralytic agent is started to determine current necessary to obtain twitch.
- 20 mA may be enough for the patient.
- Complete and document until TOF to 2/4.
- Attach 2 electrodes along the course of the ulnar nerve. (Temporal may be used.)
- Connect the lead to the peripheral nerve stimulator by inserting the jacks into the Proximal (red) and Distal (black) output jacks. Connect the other end to the patient electrodes.
- Turn the stimulator on. Select the current necessary (usually 20) for that patient to twitch when the stimuli is applied.
- Press TOF once. It will deliver a train of four pulses where each is 0.5 seconds apart. Do NOT use the other buttons on the stimulator!
- Count the number of twitches the patient had out of four (0/4, 1/4, 2/4, 3/4, 4/4.) Adjust the medication as ordered. Goal is 1/4 to 2/4 twitches.